[The ependymal lining of the median eminence in goats].

Ependymal epithelium of eminentia mediana in goats, examined under a light microscope, was found to be formed by beta 2 tanycytes, basal processes reaching the surface of zona externa and bifurcating in zona interna. The thickest is zona interna, consisting of dense fibres of different arrangement. A scanning electrone microscope revealed that the structure of the ependymal surface of eminentia mediana in goats depends on the phase of sexual activity of a given individual. In female and male animals the findings are almost identical (ependymoresorption is prevailing) in the period of quiescence (anoestrus, out of the season, April); an analogical situation was observed in females and males in the period of mating (hyperependymosecretion, October, November). The ependymal surface of eminentia mediana in female animals has also a typical structure in the preparatory pro-estrous stage of sexual cycle, when the results were almost identical with those in a hermaphrodite (secretion and resorption are almost equilibrated). The occurrence of supraependymal cells on the surface of eminentia mediana is scarce. These cells are very similar to nerve cells as to their external morphological structure. The presence of supraependymal fibres on the surface of the bottom of the IIIrd cerebral ventricle can be explained only partly by the finding of supraependymal cells. The investigations revealed that the structure of the surface of the ependymal epithelium of eminentia mediana in goats is markedly differentiated according to the sex; this confirms the participation of tanycytes in the control of the reproductive cycle.